Effect of ARC-BBBE microbial inoculant on main phytohormones in peanut root from seedling to podding stage

Phytohormones play a crucial role in regulating peanut growth and development. Our previous studies have demonstrated that the microbial inoculant ARC-BBBE, developed by our research group, effectively promotes peanut growth and enhances yield under both greenhouse and field conditions. Therefore, it is of significant interest to investigate how ARC-BBBE influences the levels and spatial distribution of major phytohormones in peanut roots. Greenhouse pot experiments revealed that ARC-BBBE significantly enhanced peanut growth and root system development. A systematic analysis of the effects of ARC-BBBE on key phytohormones in peanut roots across different growth stages showed that gibberellin A 3 (GA 3 ) content varied markedly, with predominant accumulation occurring during the early growth stage, whereas changes in indole-3-acetic acid (IAA) levels were not statistically significant. Specifically, GA 3 content in the ARC-BBBE treatment group was 1.27-fold higher than in the control group during the seedling stage. Furthermore, peanut growth parameters were significantly improved following ARC-BBBE application, particularly at the flowering stage, where plant height, above-ground biomass, root length, and root weight in the treated group were 1.24-, 1.17-, 1.13-, and 1.21-fold greater than those in the control, respectively. To elucidate the functional role of phytohormones in ARC-BBBE-mediated growth promotion, we examined the effects of exogenous GA 3 and its biosynthesis inhibitor uniconazole (S3307) on both PHNZY-23-3 rhizobial growth and peanut development. Results indicated that supplementation with 1×10 3 mg/L GA 3 most effectively promoted peanut growth at the seedling stage, while S3307 application inhibited growth. These findings provide valuable insights into the mechanism by which ARC-BBBE modulates GA 3 dynamics to enhance peanut growth, offering a foundation for future research on plant-microbe interactions and phytohormone regulation.